Long‐ and short‐term postseismic gravity changes of megathrust earthquakes from satellite gravimetry

Tanaka, Yuma; Heki, Kosuke

doi:10.1002/2014gl060559

Cited by 34 publications

(39 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This signal can be seen as a drop or a jump in the gravity change in the first three months after the quake, which rebounds as an exponential curve in the following months (Figures 1(a, b)). A similar pattern in time was found for the 2004 Sumatra and the 2010 Chile earthquakes by Tanaka and Heki (2014), who used two exponential functions to fit the data. The physical mechanism of this signal is not clear and to model it would be beyond the scope of this study.…”

Section: Co-seismic Gravity Changes By Grace Measurementssupporting

confidence: 69%

Co-seismic slip distribution of the 2011 Tohoku (MW 9.0) earthquake inverted from GPS and space-borne gravimetric data

Zhou

Cambiotti

Sun

et al. 2018

Earth and Planetary Physics

View full text Add to dashboard Cite

Data obtained by GRACE (Gravity Recovery and Climate Experiment) have been used to invert for the seismic source parameters of megathrust earthquakes under the assumption of either uniform slip over an entire fault or a point‐like seismic source. Herein, we further extend the inversion of GRACE long‐wavelength gravity changes to heterogeneous slip distributions during the 2011 Tohoku earthquake using three fault models: (I) a constant‐strike and constant‐dip fault, (II) a variable dip fault, and (III) a realistically varying strike fault. By removing the post‐seismic signal from the time series, and taking the effect of ocean water redistribution into account, we invert for slip models I, II, and III using co‐seismic gravity changes measured by GRACE, de‐striped by DDK3 decorrelation filter. The total seismic moments of our slip models, with respective values of 4.9×1022 Nm, 5.1×1022 Nm, and 5.0×1022 Nm, are smaller than those obtained by other studies relying on GRACE data. The resulting centroids are also located at greater depths (20 km, 19.8 km, and 17.4 km, respectively). By combining onshore GPS, GPS‐Acoustic, and GRACE data, we obtain a jointly inverted slip model with a seismic moment of 4.8×1022 Nm, which is larger than the seismic moment obtained using only the GPS displacements. We show that the slip inverted from low degree space‐borne gravimetric data, which contains information at the ocean region, is affected by the strike of the arcuate trench. The space‐borne gravimetric data help us constrain the source parameters of a megathrust earthquake within the frame of heterogeneous slip models.

show abstract

Section: Co-seismic Gravity Changes By Grace Measurementssupporting

confidence: 69%

Co-seismic slip distribution of the 2011 Tohoku (MW 9.0) earthquake inverted from GPS and space-borne gravimetric data

Zhou

Cambiotti

Sun

et al. 2018

Earth and Planetary Physics

View full text Add to dashboard Cite

show abstract

“…The solutions are presented in Figure 9: (a) for the 2004 Sumatra-Andaman, (b) the 2010 Maule, and (c) the 2011 Tohoku events. In general the coseismic pattern switch to the postseismic pattern where a dominantly monopolar gravity increase now occurs over the epicentral region, as has been explained by the mechanism of viscous relaxation of the upper mantle (e.g., Panet et al, 2007;Tanaka & Heki, 2014). A large decrease seen east of the epicentral region of the 2010 Maule is due to land hydrology as it disappears upon the removal of the latter signal (cf.…”

Section: Journal Of Geophysical Research: Solid Earthmentioning

confidence: 92%

Gravity Changes Due to Large Earthquakes Detected in GRACE Satellite Data via Empirical Orthogonal Function Analysis

Chao

Liau

2019

JGR Solid Earth

View full text Add to dashboard Cite

We report on the seven largest earthquakes for which we can detect unequivocal coseismic signals in the time‐variable gravity (TVG) data of the GRACE (Gravity Recovery and Climate Experiment) satellite mission during the GRACE era of 2002–2017. After reducing the land‐hydrological effect according to model Global Land Data Assimilation System, we employ the empirical orthogonal function (EOF) analysis to solve for the spatial pattern and time history of the coherent (standing‐oscillation) modes, which provide in an objective manner an overall view of the spatiotemporal scenario. The solved EOF mode for an earthquake‐induced TVG typically features a spatial pattern (along with polarity) for the coseismic jump, in conjunction with the time series showing the jump (plus possible preseismic and postseismic variability). In all cases the earthquake EOF mode solutions match well with the least squares coseismic jump in both spatial pattern and amplitude and agree generally with previous reports in the literature. We conclude according to the examined cases that the lowest earthquake magnitude threshold that can be detected by GRACE is the Mw 8.3 of the 2013 deep‐focus Okhotsk event, which in fact provides a testable case where the TVG we observe versus the seismologically derived source models may reflect different aspects of the source mechanism under different timescales.

show abstract

“…The ongoing response of the Earth's mantle to past changes in loading gives rises to additional GRD, known as glacial‐isostatic adjustment (GIA; e.g., Farrell & Clark ; Lambeck et al, ; Peltier et al, ). The height of the land also changes in response to processes such as sediment compaction (in some cases, accelerated by anthropogenic groundwater or hydrocarbon withdrawal) (e.g., Keogh & Törnqvist, ), tectonics (e.g., Tanaka & Heki, ), and mantle dynamics (Rowley et al, ).…”

Section: Projections Of Relative Sea Level Changementioning

confidence: 99%

Usable Science for Managing the Risks of Sea‐Level Rise

et al. 2019

View full text Add to dashboard Cite

Sea-level rise sits at the frontier of usable climate climate change research, because it involves natural and human systems with long lags, irreversible losses, and deep uncertainty. For example, many of the measures to adapt to sea-level rise involve infrastructure and land-use decisions, which can have multigenerational lifetimes and will further influence responses in both natural and human systems. Thus, sea-level science has increasingly grappled with the implications of (1) deep uncertainty in future climate system projections, particularly of human emissions and ice sheet dynamics; (2) the overlay of slow trends and high-frequency variability (e.g., tides and storms) that give rise to many of the most relevant impacts; (3) the effects of changing sea level on the physical exposure and vulnerability of ecological and socioeconomic systems; and (4) the challenges of engaging stakeholder communities with the scientific process in a way that genuinely increases the utility of the science for adaptation decision making. Much fundamental climate system research remains to be done, but many of the most critical issues sit at the intersection of natural sciences, social sciences, engineering, decision science, and political economy. Addressing these issues demands a better understanding of the coupled interactions of mean and extreme sea levels, coastal geomorphology, economics, and migration; decision-first approaches that identify and focus research upon those scientific uncertainties most relevant to concrete adaptation choices; and a political economy that allows usable science to become used science.Plain Language Summary The impacts of sea-level rise pose growing threats to coastal communities, economies, and ecosystems, and decisions made today-in areas like land-use policies, coastal development, and infrastructure investment-will affect exposure and vulnerability for generations to come. Thus, the usability of sea-level science is a pressing concern. Ensuring usability requires grappling with deep uncertainty in long-term sea-level projections, the relationship between long-term trends and the impacts of short-lived extreme events, and the ways in which the physical coast, as well as people and ecosystems along the coast, respond to increasingly frequent flooding. At the same time, it also requires more extensive and deliberate stakeholder engagement throughout the scientific process, as well as cognizance of the political economy of linking stakeholder-engaged science to action.

show abstract

Long‐ and short‐term postseismic gravity changes of megathrust earthquakes from satellite gravimetry

Cited by 34 publications

References 26 publications

Co-seismic slip distribution of the 2011 Tohoku (<i>M</i><sub>W</sub> 9.0) earthquake inverted from GPS and space-borne gravimetric data

Co-seismic slip distribution of the 2011 Tohoku (<i>M</i><sub>W</sub> 9.0) earthquake inverted from GPS and space-borne gravimetric data

Gravity Changes Due to Large Earthquakes Detected in GRACE Satellite Data via Empirical Orthogonal Function Analysis

Usable Science for Managing the Risks of Sea‐Level Rise

Contact Info

Product

Resources

About